EXHIBIT A

JOINT FILING AGREEMENT PURSUANT TO RULE 13d-1(k)(1)

This agreement is made pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), by and among the parties listed below, each referred to herein as a “Joint Filer”.  The Joint Filers agree that a statement of beneficial ownership as required by Section 13(d) of the Exchange Act and the rules thereunder may be filed on each of their behalf on Schedule 13D or Schedule 13G, as appropriate, with respect to their ownership of the Common Stock, par value $0.001 per share, of Sycamore Networks, Inc., and that said joint fil­ing may there­af­ter be amend­ed by further joint fil­ings.  The Joint Filers state that they each satis­fy the require­ments for making a joint filing under Rule 13d-1.  This Agree­ment may be exe­cuted in any number of coun­ter­parts, all of which taken togeth­er shall con­stitute one and the same in­strument.

IN WITNESS WHEREOF, the undersigned hereby exe­cute this Joint Filing Agreement as of the 14th day of January, 2010.

	/s/ Gururaj Deshpande *
	Gururaj Deshpande, in his capacity as Manager
	of Sparta Group MA LLC Series 4
	/s/ Gururaj Deshpande *
	Gururaj Deshpande
	/s/ Jaishree Deshpande *
	Jaishree Deshpande
*By	/s/ Servjeet S. Bhachu
	Servjeet S. Bhachu
	Attorney-in-Fact

* Mr. Servjeet S. Bhachu is signing as attorney-in-fact pursuant to powers of attorney dated January 13, 2010 granted by each Reporting Person, copies of which are filed as exhibits hereto.